2002 Z71 Tahoe. Have been battling this issue for a while now.I installed new wheel brgs(Aftermarket)a few months apart and new VSS sensors on the Trans.At first i would get my ABS engaging at low speeds and the ABS light and brake light coming on followed by the speedometer becoming eratic,when this would happen my transmission would want to go to low range as im guessing the speed sensors would not allow it to know what gear it was in.I have checked all the wires and grounds and they all seem to be intact.Over the weekend i removed the drivers side rotor and pulled out the sensor from the bearing unit and the mounting surface was very rusty and the sensor itself seemed damaged.I had an old sensor from the original wheel brg(100,000 mile brg)so i gave it a shot and cleaned and put a little dieelectric grease on there and for the first time since the problem started my ABS engaging at low speeds went away but the ABS light now stays on all the time as before it would just flash ocassionally and the speedometer still becomes erratic and when so the brake light also will flash.Question being do you guys think this wheel bearing and sensor is my problem considering it did solve one of the issues i was battling with??
Thanks in advance,

 

ttt
anyone have any ideas before i have to take this to a GM dealer?

 

alrighty, i had the same problem with my tahoe. This actually was posted in the previous years as a technical service bulletin. Chevrolet says to remove the sensor and clean the mounting surfaces with a wire brush till no rust is present. Add a rust inhibitor product such as some anti-seize to the surface afterwards then assemble. I did this to both front wheel speed sensors, worked for a day then started to act up again. It may work for you if you havent done it already. Although, if you take it apart and the sensors or wires leading to them are chaffed or injured, replace. Im still trying to figure out what the problem is if it isnt the mounting surface or sensor. Possibly it can be the wheel bearings however, i dont have any squeal present to really know if its bad or not other then some play in the front end.